This online publication provides access to both the full and
concise versions of the MARC 21 Format for Classification
Data. The "full" classification format contains detailed
descriptions of every data element, along with examples, input
conventions, and history sections. The "concise" classification
format contains abridged descriptions of every data element,
along with examples. The full and concise versions are
identified in the header of each field description.

Changes to the MARC 21 Format for Classification
Data that resulted from Update No. 19 (October 2014) are
displayed in red print. The date
located in the header of the full version of each field
indicates the last month and year of update.